Known in the art is an apparatus for thermal deburring of parts, comprising a working chamber and a worktable with bottom members for supporting parts, the bottom members alternatively sealing a charging opening in the working chamber. The working chamber communicates with oxident and fuel lines and is provided with a spark plug (cf. U.S. Pat. No. 3,666,252, U.S. Cl. 266-2, publ. 1972).
Combustion gases are discharged in this prior art apparatus after the treatment of parts through the charging opening of the working chamber after the bottom member has been lowered. The discharge of exhaust gases is only possible after they have been allowed to stay in the chamber, i.e. when their temperature has decreased owing to a heat removal from the chamber wall to a level which depends on the resistance of a flexible sealing ring mounted in the space between the bottom member and the chamber walls. The time of this exposure may range between 15 and 40 s so that the residence time of parts in the chamber also increases respectively. As a result, the deburring of parts is accompanied by an overheating of parts to temperatures which overpass the values specified for parts made of, e.g. titanium and aluminium casting alloys, plastics and rubber. In addition, it is difficult to treat parts having thin walls and fins because of eventual warping due to overheating. This limits the range of parts that can be treated as regards both the size and shape.
Also known in the art is an apparatus for thermal deburring of parts, comprising a working chamber and a bottom member for sealing the working chamber which are mounted for relative movement, an inlet valve for admission of a fuel gas mixture to the chamber, a spark plug and an outlet valve for discharging combustion products from the chamber (cf. USSR Inventor's Certificate No. 988499, Int. Cl. B 23K, publ. 1983). In this apparatus, the outlet valve is in the form of a widely used pair "valve/seat" wherein the sealing is ensured owing to an intimate contact at a collar by lapping the valve to the seat. In addition, the prior art apparatus is also provided with a thin-walled sleeve mounted in the chamber so as to define a space with the walls thereof, the sleeve ensuring a prolongation of service life of the apparatus because it prevents high temperature from acting directly upon the outlet valve.
When this prior art apparatus is used, combustion products are discharged from the chamber immediately after the working cycle is over when the outlet valve is actuated. It should be noted that while the provision of the protective sleeve allows the service life of the outlet valve to be somewhat prolonged, it is of a limited value because the valve should be repaired and worn members should be replaced.
It should also be noted that the design of the outlet valves is rather complicated and involves many parts and components; difficulty available materials are necessary for the manufacture of these valves, and auxiliary devices (electropneumatic valves, relays, and the like) are required for controlling the outlet valves.